If you don't use premium time it is hard to earn credits past tier 6. The premium tanks at tier 8 are the exception, but after a 1,000 games in any tanks it gets repetitive.

Tier 6 premium tanks are the best option with no premium time IMO. I need to play like 6 or 7 games at tier 6, for every game I play at higher tiers. There are some exception, like the the SU-152 or comet. But if you use any gold ammo, you risk going into the red.

I recommend using premium time if you play everyday. 30 day re-ups are best, in case you get to busy to play. If you can only play 2 or 3 rounds a day 180-360 days of premium aren't worth it. Of course this is just my opinion and results and preferences vary.

I've been running on standard for awhile now, and the game is significantly harder to advance in. Not using gold ammo probably is the biggest setback. Followed by the fact it takes twice as long to acquire the funds to buy new tanks. Say you safe 2 million credits playing mid tier tanks and decide to spend a day or 2 playing tier 9 and 10, chances are you will burn through those credits, with nothing to show for it.

I have only been playing for a few months and have bought about 2 months of Premium time (nice amount of free time from Night Hunt rewards). I had let it lapse a couple weeks before event and generally found that I could still make credits provided I remove the extras. No provisions, only camo for light tanks and td's that I plan to scout or snipe with. In the su-100y for example, I usually just roll in behind my team. Plus this tank is like a dump truck with a mega cannon attached, so camo is pretty pointless other than for decoration.

I still keep multi-repair and repair because an inopportune tracking has a high negative value. I either replace adrenaline with auto fire extinguisher or just try not to use Adrenaline unless I'm 100% sure I'll get an extra shot or two in to pay for it. Having adrenaline often doesn't make much difference (depends on tank) anyway. I'll pop it to try to get another shot in on a target and they'll wise up and hide until it wears off...or the other player is bad anyway (pointing flank at us and standing "proud" while they get shot up) and my team will destroy them before I get the extra reload. Only with a very high ROF tank is adrenaline almost always a guaranteed benefit (Tier 4 AC 1 sentinel is almost like an auto cannon with Adrenaline active for example).

Anyway, with those cost savings I generally find that I could slowly eke out small profits with most tanks. However, I got a free Dracular from Night Hunt and both Drac & Helsing have 150% credit earning ratios at Tier 7. On a good game *with* Premium time I can gross 80k - 100k credits, net being 45k - 65k if running provisions, popping all consumables, taking a lot of damage, and possibly firing a few prammo. So, w/o premium time, I'm looking at 40k - 67k gross credits on a decent to good game (1500 - 2500 damage). Cutting back on provisions and being a bit careful with consumables (Drac doesn't really need repair kits as much for example) and I can easily still make a 20k - 40k profit. Even if average is only +20k per game, @ just 25 games per day, that's 500k profit per day, 3.5M per week. Tier 7 missions can fairly easily add another 75k-100k per day. That's easily a Tier 9 tank every week. If you are in a clan with Supply level 6 or higher, the gradual savings from those 5%/10% consumable discounts (and 2%/5% tank repair discount) can accumulate to a lot of credits over the course of a week.

If you don't have a premium, see the credit ratio thread that was posted a pick a tank you're good with that has a decent credit ratio. I like VK 28.01 which has 119% IIRC, Tier V Leopard is 140%. In any case, I am going to stockpile credits before my premium time runs out, then wait and see if there is a big enough Xmas sale to justify buying more.

Lastly, if the right-most mission (most valuable mission rewards) is not gold/premium time, skip it every day to increase your chances. I'd guess you can easily get 2 - 4 days of Premium time per month and use it to grind out credits.

tl;dr:

Pick a free tank with a high credit ratio that you enjoy (or get 1 or 2 premiums with high ratios)

Remove provisions/camo, be stingy with prammo and consumables

Join a clan with Supply Level 6 or higher (or farm one up to that)

Skip right-most missions once per day if they are not gold or premium time to maximize free gold / premium time / (or free camo unlock)

What I can't figure out is why some tanks must continually replace equipment / consumables whether used or not while others don't. Camo disappears on some tanks too. tired of going into battle naked. Do over a 1000 damage win the battle and loose 20,000 credits.

I just started noticing the reduced credit earning the other day! on teir 5/6 battles in either my sherman or my jumbo, where I normally would bring home 14-16,000 credits after a battle, it has now been reduced to under 5 digits . ....maybe about 9,000 average! Something has changed . ...